Quantum point contacts as heat engines

The efficiency of macroscopic heat engines is restricted by the second law of thermodynamics. They can reach at most the efficiency of a Carnot engine. In contrast, heat currents in mesoscopic heat engines show fluctuations. Thus, there is a small probability that a mesoscopic heat engine exceeds Carnot's maximum value during a short measurement time. We illustrate this effect using a quantum point contact as a heat engine. When a temperature difference is applied to a quantum point contact, the system may be utilized as a source of electrical power under steady state conditions. We first discuss the optimal working point of such a heat engine that maximizes the generated electrical power and subsequently calculate the statistics for deviations of the efficiency from its most likely value. We find that deviations surpassing the Carnot limit are possible, but unlikely.Comment: 9 pages, 2 figures. Contribution to the Physica E special issue on "Frontiers in quantum electronic transport" in memory of Markus Buttiker. Published versio

Análisis de la intención de realizar comercio social en webs con herramientas sociales

El comercio social, o comercio a través de los medios sociales (también conocido como social commerce) es una de las modalidades de comercio electrónico con mayor potencial de crecimiento. Sin embargo, su estudio aún es limitado, por lo que las dinámicas y elementos que afectan a la intención de realizar comercio social requieren de una mayor investigación. La bibliografía existente principalmente analiza la intención de los usuarios de practicar comercio social en una red social, pero no en una web de comercio electrónico que tenga sus propias herramientas sociales (p. ej. foros, valoraciones de productos, etc.). Por lo tanto, la presente investigación tiene como objetivo identificar los antecedentes de la intención de comercio social en webs de comercio electrónico en las que se emplean herramientas sociales. A partir de la revisión de la literatura, se desarrolla un modelo para analizar la influencia de cinco posibles antecedentes de la intención de comercio social: calidad de la web, apoyo social emocional, apoyo social informativo, presencia social e inmersión o flow. Para ello, se realizó un estudio empírico entre los usuarios de una web de comercio electrónico que cuenta con un sistema de valoración, comentarios de productos y foros. Los datos se obtuvieron a partir de una encuesta realizada a 200 compradores, y fueron analizados mediante la técnica PLS. Los resultados indican que los elementos más racionales y emocionales de la experiencia del usuario, como son la calidad del sitio web, flow y el apoyo social emocional, son los que motivan la compra; mientras que la presencia social y el apoyo social informativo, no son significativos. Este estudio contribuye a la teoría del comportamiento del consumidor al aplicar variables predictivas de la intención de comercio social a webs con herramientas sociales. Además, los resultados ayudan a los profesionales del comercio electrónico a mejorar el uso que hacen de las herramientas sociales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Towards expenditure rules and fiscal sanity in the euro area

The study looks at primary expenditure developments in the euro area, its three largest members and four “macro-imbalances” countries for the period 1999-2009. It compares actual expenditure trends with those that would have prevailed if countries had followed neutral policies based on expenditure rules since the start of EMU. It also calculates the implications for debt trends. It finds that, all sample countries except Germany applied expansionary expenditure policies. This resulted in much higher expenditure and debt paths compared to a counterfactual neutral expenditure stance. Simple and prudent rules-based spending policies could have led to much safer fiscal positions much more in line with the EU’s Stability and Growth Pact rules. JEL Classification: E17, E61, E65, H50, H60Expenditure policies, expenditure rules, fiscal stance, public debt, sustainability

Destination Image on the DMO's Platforms: Official Website and Social Media

Tourists usually configure and develop ideas about possible destinations based on information previously gathered from both social media and the official web of the destination management organization (DMO). In spite of the relevance of said information sources, there have not been many studies evaluating how these different sources influence the destination image. This research proposes a model intended to explain the image creation process of a destination taking into account both the DMO’s online platforms and the perceived psychological distance. The proposed model is tested with an empirical study including a questionnaire which collects data from 264 participants. The validity of the model is reviewed through PLS analysis. Results show that the psychological distance does not influence the overall destination image. In addition, the overall destination image can be estimated to a larger extent when tourists approach social media as their main source of information. Implications and conclusions are discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech